a) Field of the Invention
The present invention relates to a motor having gears which comprises a gear mechanism such as a decelerating gear mechanism. It specifically relates to an improvement of a motor having gears, etc., with which unstable rotations of a rotor in the motor produced during start-up are stabilized in a predetermined direction.
b) Description of the Related Art
Conventionally, there is a motor having gears which comprises a gear mechanism such as a decelerating gear mechanism and to which an AC sync motor is applied as a driving source. In such a motor having gears, the rotational direction of a rotor is not stable during start-up. In order to stabilize the rotational direction, a shading coil is added or a lever for preventing reversed rotations (as disclosed in JP Kokai S62-260541) is provided.
This conventional use of a shading coil or a lever for preventing reversed rotations brought an attendant complicated structure and also increased the number of components. This resulted in increased time required for assembling and increased manufacturing cost. In addition, a motor employing a lever for preventing reversed rotations generates a clashing noise with reversed rotations, that is, a clashing noise occurs between a projection unit of a rotor and the lever for preventing reversed rotations. This has been a problem when the motor is used in quiet circumstances.